As semiconductors achieve higher levels of integration and ever faster switching speeds, metal wiring layers formed within the semiconductor devices are getting finer and using multiple layers. A damascene process may be used to form fine copper wiring. A physical vapor deposition may be used to form a diffusion barrier layer over an interlayer insulation film including a trench formed in the interlayer insulation film.
However, although physical vapor deposition has advantages such as a simple deposition process and good electrical characteristics, it has various disadvantages such as poor step coverage. Another disadvantage is that the thickness of a diffusion barrier layer may not be controlled precisely, down to a few angstroms (Å).
Accordingly, plasma enhanced atomic layer deposition (PEALD) may be used, in which a plasma process is introduced into an atomic layer deposition (ALD) process in which a deposition source gas used for forming the diffusion barrier layer is provided in independent pulses during controlled intervals.
However, plasma enhanced atomic layer deposition has a drawback in that the resistivity of the deposited film is increased while the uniformity of the diffusion barrier layer is decreased, relative to physical vapor deposition.